Feeding mechanism for rock drills



` Octl, 1935. J. c. CURTIS FEEDINGVMECHANISM FOR ROCK DRILLS 5Sheets-Sheet 1 Filed NOV. l0, 1932 i Nm QQ JOHN cca/775 INVENTORATTORNEY Oct. 1, 1935. l J, C. CUR-ns 2,015,922

FEEDINGYMEGHANISM FOR ROCK DRILLS Filed NOV. l0, 1952 3 Sheets-Sheet 255 BY Eg' 6 g ATroRNl-:Y v

CLVl, 1935. 1 Q CURTlS 2,015,922

FEEDING MECHANISM FOR ROCK DRILLS Filed Nov. 1o, 1952 :s sheets-sheet sJOHN C. 60E 775 lNvENToR Hg. 12 BY v ATTORNEY Patented Oct. 1, 1935UNITED vSTATES PATENT OFFICE FEEDING MECHANISM FOR ROCK DRILLS q John C.Curtis, Cleveland, Ohio, assigner to The Cleveland `Rock Drill Company,Cleveland, Ohio, a. corporation of Ohio Application November .10, 1932,Serial No. 642,015

` 21 Claims.`

This invention relates broadly to rock drills but more particularly to'feeding mechanism for rock drills of the drifter type.

One object of this invention is to provide a 55. feeding mechanism forrock drill provided with means preventing jar imparted to the Vmotor byits piston upon the reversal of its strokes, to cause a longitudinalmotion ofthe 'motor in Aa direction opposite to its feeding motion.

Another object of this invention 'is to construct a rock drill `feedingmechanism with all the parts thereof inclosed within the 'feed cylinder,thus protecting these parts against dust resulting from the drillingoperation, and conse- 151`quently reducing the wear between the movableparts. i i

' Another object of this invention is to produce an efficient 'devicefor packing the screw used in the feeding mechanism, thus affording adurable fluid tight joint between the screw and its cooperating partsand consequently increasing the efficiency of the mechanism. i

Other objects and advantages more or less ancillary to the foregoingreside in the specific construction and aggroupment of the elementspeculiar to this structure, as will become apparent from a more completeexamination of this speciiication.

In the drawings which illustrate a preferred .embodiment of theinvention: Fig. 1 is a longitudinal view partly in section, illustratingthe drilling motor with the feed piston positioned in one extreme end ofits travel. Fig. 2 is a view similar to Fig. l, illustrating tnedrilling motor and feeding piston positioned in the other extreme end ofits travel.

Fig. 3 is an enlarged sectional view of the rear portion of the feedtube.

Fig. e is a cross sectional view taken in a 401 `plane indicated by line4-4 in Fig. 2.

Fig. 5 is an enlarged sectional view of the stationary nut shown in Fig.1 and Fig. 2.`

Fig. 6 is an enlarged View of the backhead mounted on the end of thefeed tube.

Fig. 7 is a cross sectional view taken in a plane indicated by line'I-'I in Fig. 5.

Fig. 8 is a cross sectional view taken in a plane indicated by line 8--8in Fig. 6, illustrating the throttle valve in one operative position.

Fig. 9 is a View similar to Fig. 8 illustrating the throttle valve in`another operative position.

Fig. 10 is an enlarged longitudinal view of the feed piston.

Fig. 11 is a view similar to Fig. 10 but taken at right angle therefrom,.illustrating the ratchet plunger in one operative position.

Fig. `12 is a view 'similar to Fig. 11, illustrating the ratchet plungerinthe other operative position. 5 f

Fig. 13 is a cross sectional View taken in a plane indicated by lineI3--I3 in Fig.. 10.

Referring to the drawings, the rock drill shown for the purpose ofillustration comprises a cylinder I 0, within which there is reiprocably10 mounted a piston capable of delivering its blow to a cutting tool ordrill steel Il. This drill steel is equipped with lugs engageable withcorresponding jaws provided into the chuck I2, in

a manner common to 'tools of this type. e The 15 external wall of thelower portion of the cylinder IU is provided with two gibs or guides I3.The feeding mechanism comprises a feed tube I4 made of rectangular crosssection constituting a support for the rock drill. vided on its upperface with two guide-ways I5 within which the guides I 3 of the cylinderI0 are free to slide, permitting thereby the longitudinal displacementof the rock drill on the feed tube I4. For mounting purposes on a tripodor oth- 25j4 er supporting devices, the feed tube I4 is equipped with acone I6, attached thereto by any suitable means, as for instance bymeans of a weld. The right end of the feed tube which will hereafter bedesignated as front end, is closed as at 30 I'I, while the left end,which will hereafter be designated as rear end, is closed by a backheadI8 secured thereto by bolts I9.

Reciprocably mounted into the front portion of the feed tube I4, thereis a piston 20 com- 35 prising a sleeve 2l having the ends thereofformed with external threads to receive the nuts 22. Clamped between thenuts 22 and supported by the sleeve 2|, there are two rectangularpackings 23 disposed in opposite directions and capable of 40 duid tightengagement with the inner wall of the feed tube I4. Intermediatethepackings 23, there is a rectangular separator 24 capable of slidableengagement with the inner wall of the feed tube I4, but held againstrotation therein by reason of its rectangular cross section, thus thesleeve 2I being clamped to the separator 24 by the nuts 22, is also heldagainst rotation. The sleeve 2I is properly machined to rotatablyreceive the restricted end 25 of the feed screw 2E. 50 The end of thescrew 26 is threaded to receive a nut 21 for preventing the accidentalremoval of the piston 20 from the screw. Located on each end of thesleeve 2|, there are `two disks 28 and 29 which are keyed to therestricted 55 'I'his tube is pro 201 between thel nut 'an-d the tube.

end of the screw. The inner walls of the disks 28 and 29 are providedwith radially disposed ratchet teeth 36 and 3 I. Leading from the innerface of the disk 28 to the inner face of the disk 29, there are providedthrough the sleeve 2I two square passages 32. Reciprocably mounted intoeach of these passages 32, there is a square plunger 33 with the endsthereof machined to fit the teeth 30 and 3I.

Terminating the portion of the feed tube-in which the piston 20 isreciprocably mounted, there is a stationary nut 34 formed with a headshapedv to fit the internal wall of thefeed tube I4, and

secured thereto by transversally 4disposed bolts 35. Extending from thehead ofthe nut 34, there is a Vcylindrical portion or sleeve 36,provided with a threaded bore corresponding to the thread of the screw26 and capable of engagement with the latter. Secured to the nut 34,there is a packing 31 having a lip 38 in engagement with the internalwall of the tube I 4 for affording a iiuid tight joint Mounted in screwtight engagement on the sleeve 36, there is a retaining nut 39 capableof engagement with a retainer 46 for clamping the packing 31 against thefeed screw nut 34. `The relative rotation of the packing with the nut 34and retainer 4B is prevented by pins 4I which are transversely mountedthrough these parts. Intermediate its ends, the

retainingnut 33, is provide with'a transversally prerssion spring 48havingone end thereof resting against the front side wall of the slot42, while the other end is engageable with an outer flange 49terminating the busing 45. Intermediate the end of the sleeve36 and theinner flange 46 of the bushing 45, there is a packing 50.

The screw 26 is formed of two distinct portions, the portion adjacentthe piston 20, which will hereafter be designated as the screw 26 isformed with a left hand thread, WhileV the other end portion of thescrew, hereafter `designated as the screw 5I, is formed with a righthand thread. Projecting from the rear end of the cylinder I6 into thefeed tube I4 there is a tongue 52, formed with a threaded bore intowhich the'screw 5I is `rotatably mounted. To allow the passage of thetongue 52, the upper wall of the feed tube I4 is provided with a slot53, extending between the backhead I8 to the nut 34. Y

Attached to the rear ofthe tongue 52 by a bolt l54 at a point adjacentthe upper inner wall of the feed tube I4, there is the end of a strap55, preferably made of flexible material such as leather or the like.The other end of the strap 55 is affixed toa spring actuated roller 56,-rotatably mounted into the rear end of the feed tube I4. The strap canbe wound on the roller 56 and kept under tension by means of the torsionspring 51.

Rotatably mounted within the backhead I8, there Vis a throttle valve 58having attached thereto a handle-59. The throttle valve is formed with acentral bore 60 into which motive uid may be admitted from its source ofsupply. Leading from-thebore SIL-there are two radially disposed ports6I and 62. A recess 63 is also formed on the external wall of thethrottle valve, this recess is in constant communication with a venthole 64, provided in the backhead I8. Leading from the throttle valve 58into the rear end of the frontr portion of the feed tube I4, there is asmall tube 65, capable of communication with the throttle 5 valve port6I for admitting motive fluid into the rear end of the cylinder, andleading from the throttle valve 58 into the front end of the frontportion of the feed tube I4, there is another tube 65 capable ofcommunication with the throttle 10 valve passage 62 for admitting motiveiluid into the front end of the feed tube.

In the operation of the mechanism, assuming the parts positioned asillustrated in Fig. l and the throttle valve positioned as illustratedin Fig. 9, 15 pressure fluid will be admitted on the back of the piston20 through'the tube 65 to move the piston forwardly. Any pressure fluidremaining in the front endof the feed tube, Will be free to exhaust f toatmosphere through the tube 66, valve passage 2O 52, recess 53 and venthole 64. Pressure fluid admitted into the rear end of the feed tube willbe prevented to escape between the screw 26 and nut 34 by the action ofthe packing 56. The compression spring 48V acting on the ange 43 of the25 bushing 45, causes the inner flange 46 thereof to effect a constantpressure on the packing 56. This constant taking up of the packing 50 bymeans of the spring 48 Will be suicient, under normal pressure, toafford an efficient fluid tight joint. How- 30 ever when pressure iiuidis admitted back of the piston 23, a pressure will be exerted on theforward face of the bushing 45, thus cooperating with the springpressure to move the bushing toward the nut 34 and consequently producea greater com- 35 pression of the packing 58. The tightness of the jointis thereforel proportional to the tension of the spring together-withthe pressure resulting from the action of the pressure fluid on theforward end of the bushing 45. back of the piston 2i) will cause theforward movement of the latter together with the longitudinal movementof the screws 26 and 5 I. The last screw -being in engagement with thecylinder I0, its longitudinal movement will naturally be trans- 45mitted to the cylinder of the rock drill for feeding it toward the work.The screw 26 being pulled through the stationary nut 34 will effect therotation of the screws 25 and 5I in one direction. The threads of thescrew 5I being opposite to the 50 threads of the screw 26, the rotationof the former within the corresponding threaded tongue 52 of thecylinder I8 will cause the longitudinal movement of the cylinder in thesame direction as the piston 28. It can be seen that if the two screws55 are formed with an equal pitch, the movement or displacement of therock drill will be twice as fast as the displacement of the piston 26.The rock drill is displaced by a longitudinal force resulting from thelongitudinal movement of the piston 20 60 or screw 5I and by a secondforce resulting from the rotationof the screw 5I within the tongue 52.

` When the machine is fed forwardly, the strap 55 affixed to the rearface of the tongue 52, will move forwardly with the machine against thetension 65 of the spring 51. This strap being wider than the width ofthe slot 53, will close the slot behind the machine and consequentlyprevent the admission of dust or foreign matter inside the feed tube orupon the screwV 5I. 70

. vWhen it is desired to retract the rock drill from the work, thethrottle valve may be positioned as illustrated in Fig. 8 to admitpressure iiuid in front of the piston 20. Any pressure fluid remaininginto the rear end of the feed tube, will The pressure fluid admitted 40y be 'free to exhaustto atmosphere throughthe tube 65, valve port 6|,recess 63 and vent hole 64. l

Pressure fluid acting on the piston will actuate the same rearwardly,thus causing the rearward motion of the machine in a manner similar tothe one explained previously in regard to the forward movementof themachine. During the rearward movement of the machine, the strap 55, bythe action of the torsion spring 5'|, will also move rearwardly to allowthe passage of the tongue 52 into the slot 53'.

It will be observed that whenthe machine is fed forwardly or toward thework, the actuating area of the piston 20 is restricted to the annulararea extending from the screw 24 to the periphery of the piston. On theother' hand, when `the machine is fed rearwardly or awayfrom the work,the actuating area of the piston is unrestricted. The feeding powerbeing directly proportional to the actuating area of the piston, it willbe obvious that the feeding power producing the retraction of themachine from.A the work is greater than the feeding power impelling themachine forwardly, permitting thereby the withdrawal of the drill steell from the drilled hole under the most adverse conditions.

During the reciprocation of the hammer piston within the rock drill, thelatter is subjected to longitudinal vibrations or jars imparted theretoby the hammer piston upon the reversal of its strokes therein, thussubjecting the rock drill to undesirable alternative forward andbackward motions causing the rotation of the screw 26 and disks 28 and29 in alternative direction, due to the interengagement of the screw 5|with the threaded tongue 52 depending from the rock drill I6. When therock drill is fed away from the work, the `action of the pressure fluidon the front face of the piston 20, will drive the screw 26 through thestationary nut 34, thus causing the rotation of the former, and of thedisks 28 and 29, in a directionillustrated by the arrows in Fig. 12.Simultaneously, the jars imparted to the rock drill in a direction awayfrom the work, will assist the screw to rotate in the last mentioneddirection, due to the interengagement of the screw 5| with the threadedtongue 52. When the rock drill is subjected to the undesirablealternative forward motion resulting from the jars imparted thereto, thethreaded tongue 52 engaging the screw 5| will cause the rotation of `thelatter, and consequently of the screw 26 and disks 28 and 29, in adirection adverse tothat resulting from the feeding motion. However thisundesirable forward motion of the drill is prevented due to theoperation of the ratchet mechanism located within the piston 20. Whenthe pressure fluid is acting on the front face of the piston 2i! to feedthe machine away from the work, pressure iiuid will flow past the teeth3| into the passage 32 to act on one end of the plunger 33 for shiftingand maintaining the same in engagement with the teeth 30 of the disk 28.In this instance, the rotation of the disk 28 and screws 26 and 5| in adirection adverse to that resulting from the feeding motion, isprevented due to the engagement of the plunger 33 with the straight wallof the teeth 39 of the disk 28. Since the rotation of the screws 26 and5| in that adverse direction is prevented, it is obvious that theundesirable forward vmotion or rebound of the rock drill is alsoprevented due to the interengagement of the threaded tongue 52 with thescrew 5|. During the rotation of the screws and disks in a directionindicated by the arrows in Fig. 12, that is in pressure fluid on thepiston 20 for feeding the rock drill away from the work, the inclinedwall of the teeth 30 engaging the correspondingly shaped end oftheplunger 33, will force the latter away from the disk 28 against thepressure fluid the direction resulting from the action of the acting Vonthe other end ofthe plunger, thus wardly, motive fluid will pass by theteeth 3|) into the passages 32 for moving the plunger 33 in engagementwith the teeth 3|. In this instance, the screw 26 and disks 28 and 29are rotated `in the direction indicated by the arrows in Fig. 11.

`The rotation of the screw 26 causing the feeding of the rock drilltoward the work is now permitted while its rotation in the oppositedirection is prevented as previously explained. The rebounds imparted tothe rock drill in a direction adverse to its feeding motion, areautomatically checked by the engagement of the uid actuated plunger 33with the teeth of the disks 28 or 29.

Although the foregoing description is necessarily of a detailedcharacter, in order to completely set forth the invention, it is to beunderstood that the specific terminology is not intended to berestrictive or confining and it is to be further understood that variousrearrangements of parts and modification of structural detail may beresorted to without departing from the scope or spirit of the inventionas herein claimed.`

I claim:

1. The combination with a drilling motor, of feeding means thereforcomprising a feed tube having a fluid actuated reciprocable membertherein, a tongue connecting said member to Said motor for transmittingthe reciprocatory motion of the former to the latter, an opening in saidtube through which said tongue passes, a iiexible member connected tosaid motor and movable therewith for closing said opening subsequent tothe passage of said tongue therein, and means for winding said flexiblemember within said tube for opening said slot during the return movementof said motor.

2.`The combination with a drilling motor, of feeding means thereforcomprising a feed tube having a fluid actuated reciprocable membertherein,` a member connecting said motor to said reciprocable member fortransmitting the reciprocatory motion of the latter to the former, aslot in said tube through which said connecting member passes, said slotbeing gradually uncovered by said motor during the displacement of thelattery in one direction, a closing' member having one end thereofattached to said motor and movable thereby for closing said slot whensaid motor' uncovers the latter, the other end of saidclosing memberbeing constantly connected to said tube at a point exterior to the endsof said slot.

3. The combination with a drilling motor, of feeding means thereforcomprising a feed tube having a fluid actuated reciprocable membertherein, a member connecting said motor to said reciprocable member fortransmitting the reciprocatory motion of the latter to the former, aslot in said tube through which said connecting member passes, aflexible member attached to said motor and movable therewith in onedirec-` tion forclosing said slot, and means for returning said flexiblemember to its original position for opening said slot during themovement of vsaid motor in the other direction.

iportions, a fluid actuated reciprocable memberV 4. The combination witha rock drill feeding mechanism comprising a feed tube constituting asupport for the rock drill, guide-ways on the upper face of said feedtube, of a rock drill slidable on the guide-ways, a stationary elementWithin said feed tube dividing the latter into two into one of saidportions, passages for admitting motive iiuid into said last portion foractuating said member, means within said stationary element engageablewith means on said reciprocable ,member responsive to the reciprocationof the latter for causing its rotation, said reciprocable memberextending into the other of said portions'for engagement with said rockdrill, means forV transforming the rotary and reciprocatory Ymotion ofsaid member into a feeding motion and transmitting said feeding motionto said rock drill by the engagement of the latter with said member, andfurther means subjected to the action of the motive fluid for affordinga fluid tight joint between said stationary element and the inner wallof said feed tube.

5. The combination with a drilling motor, of feeding means thereforincluding a reciprocable and rotatable feed screw associated with astationary nut, means for eifecting the reciprocation of said screw toeffect its rotary motion by its association with said nut, means fortransforming said rotary motion to a feeding motion and transmittingsaid feeding motion to said motor, where- Y:by the rotation of saidscrew in one direction effects the forward feeding of said motor whilethe rotation of said screw in the other direction ef- `fects therearward feeding of said motor, the rearward feeding power transmittedto said motor being normally greater than the forward feeding powertransmitted thereto.

6. 'I'he combination with a-drilling motor, of feeding means therefor,comprising a feed tube constituting a support upon which said drillingmotor may slide, said feed tube being closed at both ends, a shaftmovably mounted within said tube, a stationary bearingV for said shaftdisposed intermediate the ends of said tube, a piston reciprocablymounted within said tube se- 1cured on the front end of said shaftagainst relative longitudinal movement therewith, a member dependingfrom said drilling motor affording a reciprocable rear end bearing forsaid shaft, passages for admitting pressure fluid into .said feed tubeto actuate said piston and shaft,

ing a fluid actuated member slidable therein connected to said motor forimparting feeding motion to the latter toward or away from the work, andfluid actuated means carried by said mem- ,ber for preventing the recoilof said motor resulting from said jars irrespective of the direction ofthe travel of said motor.

8. vThe combination with a drilling motor comprising a reciprocatoryhammer piston in the motor imparting jars thereto, of a feedingmechanism for said motor comprisinga feed tube, a member reciprocablyand rotatably mounted into said feed tube associatedy with a stationaryelement, means for effecting the reciprocatory motion of said member toeffect its rotary motion by its association with said stationary member,means for transforming said reciprocatory and rotary motion into afeeding motionl and transmitting said last motion to .said motor, andfurther means carried by said member for preventing the recoilsresulting from the jars imparted to said motor, said last means beingautomatically shifted into recoils preventing position at the beginningof each stroke of said member within said tube.

9. The combination with a drilling motor, of feeding means thereforcomprising a feed tube having a piston longitudinally movable therein,means for transmitting the longitudinal movement of said piston to saidmotor, passages for admitting motive fluid into said feed tube toactuate said piston, and fluid actuated means carried by said piston forpreventing the longitudinal movement of the latter against the motivefluid admitted into said feed tube.

l0. The combination with a drilling motor, of feeding means thereforcomprising a feed tube having a fluid actuated rotatable member therein,means for transforming the rotary motion of said member into a feedingmotion and transmitting said last motion to said motor, passages foralternatively admitting motive uid into the ends of said feed tube toactuate said member, the rotation of said member in one direction beingresponsive to the pressure of motive fluid admitted into one end of saidfeed tube and its rotation in the other direction being responsive tothe pressure of motive fluid admitted in the other end of said feedtube, and means responsive to the action of the pressure uid effectingthe rotation of said member for preventing the rotation of the latter ina direction adverse to the direction of rotation responsive to thepressure of motive Huid acting on said member.

1.1. The combination with a drilling motor, of feeding means thereforcomprising a support upon which said motor may slide, a fluid actuatedmechanism reciprocably and rotatably mounted into said support, meansfor transforming the reciprocatory and rotary 4motion of said mechanisminto a feeding motion and transmitting said last motion to said motor,means for admitting motive fluid to said mechanism for actuating thelatter in one direction, and further means permitting a step by steprotation of said mechanism in the Idirection responsive to the action ofthe motive iiuid admitted thereto and preventing its rotation in theopposite direction said last means being automatically shifted into theproper operative position when pressure fluid is admitted to saidmechanism for actuating the latter in the other direction.

12.*The combination with a rock drill, of feeding means thereforcomprising a uid actuated motor, means for transforming the motion ofsaid motor into a feeding motion and transmitting said last motion tosaid rock drill, means for admitting pressure fluid to said motor foractuating the latter into feeding motion, and further means forsimultaneously preventing the actuation of said motor in a directionadverse to that of said feeding motion, said last mentioned means beingautomatically shifted into operative position irrespective of the senseof direction of said feeding motion,

13. The combination with a drilling motor, of feeding meansV thereforcomprising a feed tube having a member reciprocably and rotatablymounted therein, means subjected to the action of motive uid foreffecting the reciprocatory motion of said member, other meansassociated with the latter for effecting its rotary motion responsive toits reciprocatory motion, further means for transforming thereciprocatory and rotary motion of said member into a feeding motion andtransmitting said last motion to said motor, and a ratchet mechanismautomatically connected to said member for permitting a step by steprotation of the latter in one direction and preventing its rotation inthe other direction irrespective of the sense of the feeding motion ofsaid motor.

14. The combination with a drilling motor, of a frame for said motor onwhich the latter is free to slide, of a feeding mechanism within saidframe, a feed transmitting member connecting said feeding mechanism tosaid motor, a slot in said frame through which said member passes, thedistance between one end of said frame and one end of said slot beingconsiderably less than the overall length of said slot, and meanscapable of entirely covering said slot subsequent to the passage of saidmember therein, said means remaining between the ends of said frameirrespective of the position of said motor on the latter.

15. The combination of a frame, of a member reciprocably mountedthereon, of a slot within said frame through which a portion of saidmember is free to pass, of means for covering said slot subsequent tothe passage of the portion of `said member therein, said meanscomprising a flexible member attached to said reciprocable member andmovable therewith in one direction for closing said slot, and furthermeans for returning said flexible member to its original position foropening said slot during the movement of said reciprocable member in theother` direction, I

16. The combination with a drilling motor, of a feeding mechanismtherefor including a feed tube, a motive uid actuated memberreciprocable therein, a feed transmitting connection between said memberand said drilling motor, and means associated with said feedingmechanism including a denticulated element and a pawl element, one ofsaid elements being automatically movable in operative engagement withthe other for preventing motions of said member other than themotion'imparted thereto by the action of the motive fluid thereon andirrespective of its sense of direction. j

17. The combination with a drilling motor, of a feeding mechanismtherefor comprising a feed tube, a power actuated member longitudinallymovable within said tube for imparting feeding motion to said motor, afeeding motion transmitting connection between said member and saidmotor, a longitudinal movement preventing device associated with saidmechanism comprising a duality of elements one movable relatively to theother, means on each of said elements capable of interengagement forpreventing the longitudinal movement of said member in a directionadversed to that of its feeding motion, and means for automaticallycausing the interengagement of said elements irrespective of the senseof direction of the feeding motion of said member.

18. The combination with a drilling motor, of 5 mechanism responsive tothe reciprocatory inow tion of said member for imparting rotationthereto, means for transforming the reciprocatory and rotary motion ofsaid member into a feeding motion transmitted to said drilling motor,passages for admitting pressure iiuid into said feed tube 15 foractuating said piston, a ratchet mechanism associated with said membercomprising a duality of toothed elements connected to said member forrotation therewith, and non-rotatable means automatically movable intoengagement 20 with one of said toothed elements for preventing therotary motion of said member in a direction adverse to the direction ofrotation responsive to the action of the pressure fluid on said piston.

19. The combination with a drilling motor 25 comprising a reciprocatoryhammer piston in the motor imparting jars thereto in two directions,means associated with said motor for imparting feeding motion theretoindependently of said jars, and a jar resisting mechanism including aduality 30 of elements one movable relatively to the other due to thejars imparted to said motor, teeth formed on one of said elements, andmeans for automatically causing the engagement of the other of saidelements with the teeth of the for- V35 mer for checking the jarsimparted to said motor in a direction adverse to that of said feedingmotion.

20. The combination with a drilling motor comprising a reciprocatoryhammer piston in the 40 motor imparting jars thereto in two directions,power actuated means associated with said motor cooperating with thejars transmitted to the latter in either direction for imparting feedingmotion thereto, and jars resisting means associated 45 with said motorcomprising a duality of interengageable elements, automatically movablein operative engagement for checking the jars imparted to said motor ina direction adverse to that of said feeding motion.

21. The combination with a drilling motor comprising a reciprocatoryhammer piston in the motor imparting jars thereto in two directions,power actuated means associated with said motor for imparting feedingmotion thereto, and jars re- 55 sisting means associated with said motoroomprising a toothed member and an element in engagement with the teeththereof, said teeth and element being formed and disposed in a mannerpermitting the feeding motion of the motor irre- 60 spective of saidengagement but checking the movement of the motor in a directionadversed to that of its feeding motion.

JOHN C. CURTIS. 65

